Manually operable crimping tools



J. A. LEE

MANUALLY OPERABLE CRIMPING TOOLS Oct. 19, 1965 Filed Dec. 23, 1963 3 Sheets-Sheet 1 7 o l9 8 9 2 9 1 I0 15 Oct. 19, 1965 J. A. LEE 3,212,315

MANUALLY OPERABLE CRIMPING TOOLS Filed Dec. 25, 1963 s Sheets-Sheet 2 Oct. 19, 1965 J. A. LEE 3,212,315

MANUALLY OPERABLE CRIMPING TOOLS Filed Dec. 23, 1963 3 Sheets-Sheet 3 United States Patent 3,212,315 MANUALLY UPERABLE CRIMPHNG TOOLS James A. Lee, Highworth, England, assignor to Plessey UK. Limited, a British company Claims priority, application Great Britain, Jan. 11, 1963, 1,343/63; Sept. 6, 1963, 35,339/63 Filed Dec. 23, 1963, Ser. No. 332,974 7 Claims. (Ci. 72-407) This invention relates to manually operable crimping devices and is particularly though not exclusively intended for the actuation of a crimping tool which is suitable for use with a wide range of crimp diameters. One crimping tool of this character is described and claimed in our co-pending U.S.A. application No. 111,866, filed May 22, 1961, which later became Patent No. 3,133,461. When there is a considerable difference in diameters between the smallest and the largest crimp to be performed by the same tool, it has hitherto been difficult to ensure that each crimp, irrespective of its diameter, receives the requisite amount of compression, and it is an object of the present invention to provide an improved manually operable crimping device which automatically ensures adequate compression of the largest crimp accepted by the device while avoiding substantial over-crimp in the case of the smallest crimps for which the device is intended.

According to the invention the crimping stroke is effected by means of a rotary-cam-and-follower device in which the cam is restricted to unidirectional rotation by means of a sprag device, for example a ratchet wheel cooperating with a keep pawl, and a buffer spring is provided which is actedupon by the force transmitted from the cam to the crimping tool. Preferably this spring is interposed between the cam follower and the crimping tool. It will be readily appreciated that with this construction th buffer spring will be bodily moved during the approach movement of the crimping jaws to the workpiece and will then be compressed by an amount corresponding to the residue of the cam-follower stroke, which terminates when the apex of the cam is reached; the final compression of the spring, and thus the crimping force applied to the jaws, thus increases with the diameter of the workpiece susbtantially in proportion with it, and as a result the crimping pressure on the crimping area will be independent of the workpiece diameter provided that the axial length of all crimps is approximately equal, as is the case when using the crimping tool described in our abovementioned application.

When th crimping device according to the present invention is so constructed as to minimise friction losses, for example by forming the cam as an eccentric having an operating rim mounted on anti-friction bearings, that the energy stored in the spring will, once the eccentric has passed its dead-centre position, cause rapid further rotation of the cam in the direction permitted by the ratchet or the like. As a result the cam is liable to overshoot its fully open position, at which the crimped connection is intended to be removed from the device, and thus to cause the crimping jaws again to re-engage the crimped joint under some pressure. If this happens, th ratchet device will cause this pressure to be maintained because it prevents the cam from returning to the jaws-open position. This occurrence is clearly highly undesirable, and a subsidiary feature of the present invention is intended to avoid such accidental re-engagement and thus to ensure that the crimp connection can be readily withdrawn.

According to this subsidiary feature a lost-motion device is preferably interposed between the manually operated drive element, for example a ratchet wheel, and the cam element (eccentric or cam) allowing the cam element, after passing the dead-centre position, to ad vance independently of the drive element by a sufficient angle to move through the crimp-removal position and then bounce back to at least the fully open position be fore becoming re-engaged with the cam-drive element to permit the next crimping operation to be started. Resilient indexing means are preferably provided to prevent the ratchet wheel or the like from taking any part in this rapid forward movement of the cam element after completion of the crimping stroke. It will be appreciated that in this manner it is assured that each crimping operation corresponds to a complete revolution, or a predetermined integer sub-multiple of a complete revolution, of the ratchet wheel or equivalent cam-drive element and this, according to a further subsidiary feature of the invention, is utilised to obtain an indication of the number of computed crimping operations by providing a crimpcounting device which is arranged to be actuated to effect a count each time the ratchet wheel has performed a complete revolution or the appropriate sub-multiple of a revolution, as the case may be.

Various embodiments of the invention will now be described with reference to the accompanying drawing, in which:

FIGURE 1 is an elevation, partly in section, of a crimping tool, the die portion being broken away,

FIGURE 2 similarly illustrates a modification,

FIGURES 3 and 4 are end elevations showing respectlvely two forms of modified cam-and-ratchet mechanism, adapted to take the place of the cam-and-ratchet mechanism shown in FIGURES 1 and 2,

FIGURE 5 is a side elevation, partly in section, with one of the body half-shells removed of a modified embodiment combining features similar to those described with reference to FIGURES 1 and 3, and

FIGURE 6 is a section, substantially on line 66 of FIGURE 5.

Referring now first to FIGURE 1, the die-actuating pin 1 of a crimping tool is guided in a bore 3 of the tool body 2. Mounted for rotation in the same tool body is the shaft 4 of an actuating cam element in the form of an eccentric 5, which is actuated by a ratchet wheel 6, to which it is connected for common rotation. A multi-disc spring, forming, together with a skirted piston 9 resting against the pin 3, a heavy-force compressionspring system 7, is slidable in a bore 8 of the body 2, which bore is coaxial with the bore 3, serves to transmit thrust from the circumference of the cam 5 to the pin 1. A cam-follower thrust pad 10 slides in a skirt 9a of the piston 9 and is further guided in the piston by a stem 11. The space insid the skirt 9a between the body of the piston 9 and the thrust pad 10 is filled with a spring pack 12 of known construction. The body 2 is provided with a pistol-grip handle 13 to which a bell-crank lever 14 is pivoted at 15. The longer arm of the lever 14 extends at an angle to the handle 13 so that it can be pulled towards the latter by the fingers of a hand holding the tool, while the shorter arm of the lever 14 serves to move an actuating pawl 16 which is urged by a spring 17 into engagement with the teeth of the ratchet wheel 6; a retainer or keep pawl 18, applied by a spring 19, prevents reverse rotation of the ratchet wheel 6 when hand lever 14, after being operated by pressure of the fingers, is released and returns to its illustrated position under the action of a tension spring 20.

Assuming that the cam at the beginning of an operation is in the position in which its smallest radius is in contact with the thrust pad 10, and that the jaw-actuating thrust rod 1 and the transmitting member 7 are fully withdrawn into contact with thecam, repeated operation of the hand lever 14 in trigger fashion will turn the cam and displace the thrust member 7 and rod 1 outwardly, thereby moving the dies of the crimping tool towards the closed position. This proceeds without compression of the spring 12 until the dies make contact with the workpiece. When such contact is made, further rotation of the cam or eccentric 5 by subsequent operation of the hand lever 14 will compress the spring 12, thereby applying to the workpiece a progressively increasing crimping force, the final magnitude of which is determined by the original dimensions of the workpiece, that is to say the amount of stroke of the cam follower remaining between the point of contact with the workpiece and the said maximum-radius position of the eccentric 5 and by the amount by which the workpiece yields due to the crimping pressure. Since the pawl 18 prevents the direction of rotation of the cam from being reversed, the jaws cannnot, once they have made contact with the workpiece, be disengaged from the latter until the full stroke has been completed, whereafter further operation of the lever 14 will turn the cam 5 to a position at which progressively smaller radii are in contact with the thrust pad 10. On the other hand the length of the above-mentioned residual stroke will be proportional to the thickness of the workpiece, so that for workpieces of similar construction the maximum crimping pressure achieved during the crimping operation will also be substantially proportional to that diameter.

FIGURE 2 illustrates a modified construction of the cam, in which rollers 21. guided in radial slots 22 of a pair of side plates 23 are interposed between the circumference of the cam 24 and the end-surface of the cam-follower thrust pad 25. This thrust pad 25 is hollowed to form part of a cylinder surface whose axis is parallel to the axis of shaft 4, and the cam 24 itself has a substantially elliptical profile with the point of intersection of its major and minor axes aligned with the axis of shaft 4. Two carrier side plates 23 are mounted on the shaft 4, one at each side of the cam 24 and are rotatable about the shaft, and they are lightly spring-indexed in the housing as indicated at 26 to each of the four possible positions in which the rollers are arranged as shown in the drawings, with one roller just about to enter the gap between the cam 4 and the face of the thrust pad 25. When the cam is now rotated by operation of the hand lever 14, the said roller is trapped in the wedge gap between the cam face and the thrust pad 25 and will, during further rotation of the cam 24, roll in epicyclic motion along the surface of the cam and the opposed surface of the thrust pad, thus transmitting the thrust of the cam to the pad, thus greatly reducing friction compared to that which occurs between the cam 5 and the thrust pad 10 in the embodiment of FIGURE 1.

FIGURES 3 and 4 illustrate modifications of the cam and ratchet mechanism which ensure ready removability of the crimp when the cam friction is low.

Referring to FIGURE 3, an eccentric or cam is rotatably mounted on a cam carrier 34, which latter is coaxially connected with a ratchet wheel 36 for common rotation therewith. In order to force the cam 35 to rotate with the cam carrier 34 when the latter is operated by a pawl 46 to compress a buffer spring interposed between the cam follower 10 and the crimping jaws of a crimping tool according to FIGURE 1, the cam carrier 34 is equipped with a single pawl 37, while the bore of cam 35 is formed with two diametrically opposite pawl apertures 38. When, by repeated operation of the pawl 46, the cam 35 has been moved past the illustrated position at which the follower 10 reaches the end of its springcompress-ion stroke, the residual energy stored in the spring after completion of the crimping operation will cause the cam 35 to start rotating rapidly in the same direction in which it hitherto had been driven by the ratchet gear 46, 36. The pawl 37 allows the cam to do so Without forcing the ratchet wheel 36 to participate in this rotation. As described above, the cam 35 will move beyond the full-release position corresponding to a half-turn of the cam, and will thus re-engage the follower 10 and begin to compress again the buffer spring. Due to energy dissipation its kinetic energy will, however, not be suflicient to complete the full 360 of revolution which would be necessary to re-engage the same pawl aperture 38 which it had previously engaged. The spring will therefore be able to reverse the direction of rotation of the cam 35 and the cam will now start rotation in the direction opposite to that in which it was previously driven by the ratchet gear 46, 36. In doing so the cam will allow the pawl 37 to engage the second pawl aperture 38 when the cam 35 is in a position corresponding to full opening of the jaws, whereafter further rotation of the cam in this reverse direction is prevented by the engagement of the pawl 37 into the second pawl aperture 38 and the engagement between the ratchet wheel 36 and the actuating pawl 46. The tool will therefore come to rest with its jaws fully open, ensuring ready withdrawal of the crimped connection and ready insertion of the next connection to be crimped, and moreover only one half of a revolution of the ratchet wheel 36 is necessary for each crimping operation.

L'r order to prevent the ratchet wheel 36 from any participation in the continued forward movement of the cam 35 following the completion of a crimp, the ratchet wheel is preferably equipped with two spring-loaded indexing detents 39 of which, immediately following the passage of the cam 35 through the maximum-compression position, one or the other engages a roller 40 mounted in the frame of the crimping tool. When, after insertion of the next connection, the next crimping operation is started by actuation of the pawl 46, the spring 39a of the detent 39 which engages the roller 40, is initially loaded. When the detent then has passed through its maximumdefiection position moving past roller 40, the stored energy of its spring 39a can be utilised for causing the ratchet wheel 36 to race ahead of the pawl 46 until any slack between the crimping jaws and the connection to be crimped has been taken up. This reduces further the time required to perform each crimping operation. If preferred, the positions of the detents 39 and roller 40 may be reversed, one spring-loaded detent being provided in the frame of the tool, and two rollers being carried on the ratchet gear 46 in diametrically opposite positions.

In order to obtain a ready check of the number of crimping operations performed, a crimp-counter 41 is provided. The latter has an operating lever 42 which is engaged by each detent 39 (or each roller) as it passes a predetermined position during the execution of a crimp, thus adding a unit to the count. It will be readily appreciated by those skilled in the art that when a cam arranged to produce a number of complete crimping cycles in each revolution is employed, for example in the case of the twostroke cam 24 of FIGURE 2, the construction of FIGURE 3 will be modified by proportionally increasing the number of the pawl apertures 38 in the ratchet wheel 36 and of the spring-loaded detents 39 or rollers carried by the ratchet wheel, so as to produce a crimping cycle which is substantially identical to that described with reference to FIGURE 3.

FIGURE 4 shows a modification which is somewhat simpler in construction but does not offer the same saving in crimping time. In the construction of FIGURE 4 the connection between the ratchet wheel 36 and the cam 35 is effected by a drive pin 43 on the cam 35, which engages into a part-annular slot 44 in the ratchet wheel, the cam being freely rotatable on the shaft 45 which carries the ratchet wheel 35. During the compression of the buffer spring 12 of the crimping tool, the pin 43 is in contact with the leading end of the slot 44 as shown, while when the cam 35 has passed its dead-centre position, the cam is free, under the action of the spring acting load on the cam follower It), to move on in the same direction to and beyond the position in which the crimping jaws are fully open, for the greater part of a complete revolution (or crimping cycle), and then to bounce back under the action of the spring-loaded follower 1% until finally the cam comes to rest in the fully open position, with the pin 43 approximately half-way along the groove 44. A spring 47 urging the cam to the posi tion in which the pin 43 engages the leading end of the slot, may be arranged in the groove 44 as shown. If desired a spring-detent device similar to the device 39, 40 in FIGURE 3 may also be provided for the ratchet wheel 36 of FIGURE 4, although only a single indexing position will be provided in the case of a single-lift cam. If a counting device similar to the counter 41, 42 is associated with the ratchet wheel 36 of FIGURE 4, it should be arranged to be operated only once for each complete revolution of the ratchet wheel 36, if, as shown, the cam 35 is of the single-lift kind.

FIGURES 5 and 6 illustrate a practical form of a crimping tool incorporating the basic features illustrated in FIGURE 1 in conjunction with those illustrated in FIG- URE 3. The same reference numbers as in the said figures have been applied to corresponding parts, even though some parts, such for example as the actuating pawl 16, are somewhat differently arranged. The embodiment of FIGURES 5 and 6 also shows a crimping head 59, which is attached to the body 2, and in which four crimping jaws 1A, 1B, 1C and ii) are guided in such a manner that the crimping aperture F formed by the four jaws remains square when jaw 1A, which is connected ot the actuating pin 1, is moved longitudinally of the latter. I aw 1D remains stationary during the crimping operation but can be moved, against a light spring IE, to permit lateral insertion of a connection to be crimped into, and lateral removal of the ready crimped connection out of, the crimping aperture F. The operating hand lever 14 is shown in full lines in its normal postion, and is also shown, at 14a, in chain-dotted lines in the position which it assumes at the end of its maximum stroke towards the pistol-grip handle 13, when a rubber buffer 14b makes contact with the handle 13.

The housing 2 is made in two parts 2A and 2B to facilitate assembly of the internal parts of the tool; the two parts 2A and 2B are finally secured to each other by a number of screws or bolts 51. The shaft 45 on which the ratchet wheel 36 is secured, is mounted in the housing 2a by means of needle roller bearings, the needle rollers being shown at 48, while a further ring of needle rollers 49 is interposed between the eccentric or cam 35 and the cam carrier 34. In the case of an eccentric 35, the ring of rollers 49, or an additional ring of similar rollers, is preferably interposed between a rim portion of the eccentric, which makes contact with the cam follower 10, and a core portion which thus causes the rim portion to reciprocate the follower without sliding relative thereto.

The cam follower is combined with the spring 12 in a sub-assembly unit 52 which also comprises a sleeve 53 resting in a suitable bore 54 of the housing portions 2A and 2B. The spring 12 is interposed between the flanged piston 9 and a flange 56 of the stem 11. The piston 9 is guided in a bore which is provided in an end portion 55 of the sleeve 53, and whose diameter is smaller than that of the spring 12, and the flange 56 of the stem 11 rests against a perforated end plate 57 which engages threads in, and closes, the free end of the sleeve 53. A light spring 58 urges the assembly towards the cam 35, so as to keep the cam follower 10 in contact with the cam surface.

What We claim is:

l. A manually operable crimping device comprising in combination a frame member including a handle, means for guiding at least one crimping jaw relative to said frame member, an output element at least operatively connectable to such jaw and guided in said frame member for operative movement in one direction and return movement in the opposite direction, an endless cam mounted in the frame member for rotation about an axis, said cam having at least one point of maximum eccentricity, a cam follower in contact with said cam, and movable with the output element, a cam-drive element, a hand lever pivoted to said frame for movement towards and away from the handle, unidirectional coupling means causing movement of the lever towards the handle to produce rotary movement of the cam-drive element in a predetermined direction while permitting free movement of the lever away from the handle, sprag means preventing rotation of the cam-drive element opposite to said predetermined direction, a buffer spring so arranged as to be subjected to the force opposed by the output element to operative movement transmitted to it from the cam by the cam follower and, interposed between the cam-drive element and the cam, a lost-motion device allowing the cam, when such point of maximum eccentricity has passed the cam follower, to advance in dependently of the drive element by a sufficient angle to move through a crimp-removal position and then bounce back to at least a fully open position before becoming re-engaged with the cam-drive element to permit the next crimping operation to be started.

2. A crimping device as claimed in claim 1, which includes a cam element and a cam-drive element mounted on the device for independent co-axial rotation, said lostmotion device including a surface of revolution formed on one of said elements and having at least one engagement recess, and a spring-loaded pawl carried by the other element for engagement with said at least one recess to transmit driving power from the drive element to the cam in a predetermined direction while allowing the cam to overtake the drive element when moving in the said direction relative to the drive element.

3. A crimping device as claimed in claim 2, wherein pawls and engagement recesses are so distributed round the common axis of rotation of the cam and drive element as to permit mutual engagement of at least one pawl and recess in a plurality of relative rotational positions uniformly spaced by angles corresponding to one half of a complete crimping cycle.

4. A crimping device as claimed in claim 1, which includes a cam element and a cam-drive element mounted for rotation about a common axis, the lost-motion device including an aperture in one of said elements extending round said axis for less than a full circle, a coupling dog carried by the other element to project into said aperture, and spring means urging said dog into engagement with said one element at one end of said aperture.

5. A crimping device as claimed in claim 1, which includes resilient indexing means operative to prevent the drive element from participation in the rapid forward movement of the cam element after completion of the crimping stroke.

6. A crimping device as claimed in claim 5, including a crimp-counting device arranged to be actuated to effect a count each time the cam-drive element has completed so much of a complete revolution as corresponds to a complete crimping cycle.

7. A crimping device comprising a frame, an output element for effecting crimping operations relative to the frame and an actuator element, both said elements being guided in the frame for forward and return movement, means for producing forward movement of the actuator element to a predetermined point, and means for varying the forward movement of the output element according to the force opposed to such movement comprising a butter spring interposed in series between the actuator element and output element.

References Cited by the Examiner UNITED STATES PATENTS 326,897 9/85 Brooks. 1,483,714 2/24 Brooks. 1,667,563 4/28 Perrin. 2,006,396 7/35 Jorgenson 30363 2,898,790 8/59 Lazar et a1. 3,012,456 12/61 Dracka 81 52.4 3,133,461 5/64 Walton.

WILLIAM FELDMAN, Primary Examiner.

MICHAEL BALAS, Examiner. 

